with ammonium below detection limits. The total organic carbon 

 concentration was among the three highest of the sampled wetlands . 



The boron concentration at the Oilmont site was among the highest 

 for the sample set. Arsenic and iron concentrations were also 

 relatively high, but well within the range shown by hydrologically 

 similar sites. Other analyzed trace elements were below detection 

 limits. 



Chenical history. No chemical data other than that from the June 

 1994 sampling are known from this site. No prior sampling is 

 known, and when revisited 3 months later the site lacked any free 

 water. Under normal circumstances water levels are now controlled 

 by the combination of a drainage culvert and road berms. No 

 apparent surface water route exists for flushing solutes beyond the 

 neighboring basin linked by culvert to the sample site, and the 

 site may be accumulating salts as a result. 



Sedinents. Extractable boron and arsenic concentrations are near 

 the high end of the range for hydrologically similar sites. Other 

 trace elements which were detected in sediments occurred near or 

 below median values for hydrologically similar sites. The arsenic 

 concentration exceeded the average value for soils and other 

 surficial material of the western U.S. by about 20%; the boron 

 concentration exceeded the western U.S. average by a factor of 

 four. 



The desiccated playa surface displays concentric zonation of 

 precipitate textures and mineralogy. Precipitate facies observed 

 include carbonate cementation of littoral sand and gravel; earthy, 

 anhedral ef f loresences on the higher-elevation playa surfaces; and 

 euhedral gypsum(?) near the center of the playa. 



